The present invention relates to wireless communication technologies, and in particular, to multimode multiband wireless devices.
In modem wireless communications, wireless signals transmitted by mobile devices are regulated in frequency bands defined in various standards and protocols. For example, Universal Mobile Telecommunications System (UMTS) and evolved UMTS Terrestrial Radio Access (E-UTRA) define many of these cellular bands for mobile communications, as shown in FIGS. 1A-1D. Different cellular bands typically utilize different amplifiers, which require multiple power amplifiers in a multi-band wireless device. The proliferation of cellular bands has increased the number of power amplifiers, and thus the costs and sizes of the wireless devices.
A serious challenge to mobile RF communications is that wireless devices services operate in multiple bands that can interfere with each other and with other wireless services. Examples of other wireless services include WiFi, global positioning system (GPS), satellite digital audio radio (SDARS), digital terrestrial television (DTV), digital video broadcasting (DTB), FM radio, NFC, navigation, and other satellite and terrestrial broadcast services. Many of these services operate immediately adjacent to cellular bands. These other wireless services can generate noises that interfere with mobile RF communications. Moreover, many mobile communication devices provide functions in cellular communications as well as many of these other wireless services. For example, many smart phones can provide mobile RF communications, and also include functionalities for WiFi, Bluetooth, GPS, DTV, FM radio, NFC and other satellite or terrestrial broadcasting and communication services.
In cellular communications, uplink means transmission from terminals to base stations. Downlink means reception from terminals to base stations. There are two types of duplexing for uplink and downlink: frequency-division duplexing (FDD) and time-division duplexing (TDD). In FDD, uplink and downlink use different frequencies. In TDD, uplink and downlink use the same frequency. In this application, the uplink frequencies are used for FDD bands as illustrative examples.
In the 2.3 GHz to 2.7 GHz frequency range, as shown in FIG. 1A, cellular bands and the WiFi coexist in close frequency range. Specifically, Band 38 (2.570-2.620 GHz), Band 7 (2.500-2.570 GHz), Band 40 (2.300-2.400 GHz), and Band 41 (2.496-2.690 GHz) are very close to the WiFi band (2.400-2.483 GHz) and SDARS band (2.320-2.345 GHz). As shown in FIG. 2A, the RF signals in the cellular Bands 38, 7, 40, 41 amplified by a cellular transmission amplifier 150TX and transmitted by antenna 160 are often coupled into an antenna 110 and an amplifier 100RX in a WiFi receiver, which creates too much noise for the WiFi receiver. Conversely, as shown in FIG. 2B, WiFi signals amplified by the transmission amplifier 100TX and transmitted by the antenna 110 can be coupled into the antenna 160 and the amplifier 150RX in the cellular band circuit, which interferes with the reception of the RF signals in the cellular Bands 38, 7, 40, 41. The interferences between the WiFi band and the cellular bands can prevent mobile devices from simultaneously operating in a cellular network and a wireless local network (WLAN).
Similarly, in the 0.7-1.5 GHz range, as shown in FIG. 1B, DTV CH 51, 52 are right next to cellular bands 12, 17. The noises from these cellular bands circuit can significant affect the reception of DTV signals. Additionally, in the 1.5-2.0 GHz range, as shown in FIG. 1C, GPS frequency (1.575 GHz) is overlap with cellular band 24 downlink frequency (1.525-1.559 GHz). The noises from cellular band can significant affect the reception of GPS signals. There is therefore a need to provide RF signal amplification spanning multiple cellular bands without increasing the number of power amplifiers, device size, and cost. There is also a need to provide wireless communications simultaneously with wireless services such as WiFi, GPS, SDARS, DTV, digital terrestrial television (DTV), FM radio, NFC, satellite navigation, and satellite broadcast.